OAuth flow doesn't just work with my agent (moo) for lack of OASM

[pcarrier]

GitHub Copilot MCP uses OAuth 2.0 Protected Resource Metadata (RFC 9728). When moo tries to discover the OAuth endpoints, it:

• Fetches https://api.githubcopilot.com/.well-known/oauth-protected-resource/mcp/insiders
• Gets authorization_servers: ["https://github.com/login/oauth"]
• Tries https://github.com/login/oauth/.well-known/oauth-authorization-server
• Gets 404 — GitHub doesn't publish OAuth Authorization Server Metadata.